MWTech YotaStation what's inside?

Question

Yota

Tell me about the MWTech YotaStation M18 device, as I understand it, the 4G modem is already built into this box? Most of all, the questions are, is it really possible to change the SIM card there? And how well does it work as an antenna? We need it for a mini office, but the 3G whistle catches badly there, but with the antenna, the neighbors said they had a good connection.